Jeremy Corbyn should recognise he cannot return Labour to power and quit for the good of the party, a pro-Brexit MP said.
Frank Field praised Mr Corbyn for focusing on public frustrations with the impact of globalisation but said his pitch was tainted by "serious claptrap" in other areas.
The embattled Labour leader has rejected calls to resign after facing a backlash over his lacklustre performance in the EU referendum campaign.
Mr Corbyn is facing a vote of no confidence from some of his MPs, as many express concern at the possibility of him leading the party into a snap autumn general election.
He insisted he will be carrying on and "making the case for unity" - beginning with a speech on immigration and the consequences of Brexit later today.
But Frank Field said he should use the speech to follow Mr Cameron and announce his departure.
"One of the dilemmas that we have is that Jeremy is the only senior politician who has tried to grapple with and put forward views of that group of the electorate who are the losers by globalisation," he told BBC Radio 4's Today.
"Jeremy's problems are that he packages this with serious claptrap. For example our defence policy that we will have Trident, we will renew Trident but of course we won't have any weapons, has our supporters and probably the rest of the country lying down on the floor and yelling with rage or just simply crying
"We are into an era of new politics where those people who have lost out clearly by globalisation, for the first time have found their voice through the referendum to saying in this country 'enough is enough'.
"What Jeremy has been trying to do, with his social justice programme, is begin to answer those questions that are posed by the losers of globalisation but he clearly isn't the right person to actually lead the party into an election because nobody thinks he will actually win.
"I would very much like him to do that and set the debate going with that kind of flavour."
He sounded a note of caution about the chances of ousting Mr Corbyn, noting that the membership - including many who signed up on the back of the leader's campaign - remained "very clearly in favour of somebody like Jeremy".
And he said he was unable to identify the best replacement, adding that "we don't want the same old claptrap from the Blairites either".
